1. Field of Invention
This invention relates generally to electronic assemblies and more specifically to testing electronic assemblies.
2. Discussion of Related Art
A need to test electronic assemblies frequently arises in connection with the manufacture or repair of electronic systems. An assembly may be tested by applying a pattern of stimulus signals to the assembly and comparing signals generated in response to an expected pattern of signals. In complex systems, numerous stimulus signals may be applied to an assembly and numerous response signals be measured during a test. To perform testing in an acceptable period of time, automatic test equipment is frequently used. The automatic test equipment can be programmed to quickly generate stimulus signals in a desired pattern and compare the response signals to an expected pattern.
To be able to generate and measure test signals of many different forms, test systems are frequently constructed with multiple instruments. Each instrument may execute a process that is a part of a full test. Frequently, the test processes executed by instruments include generation of stimulus signals, measurement of response signals and processing that either defines the stimulus signals or analyzes the responses. For example, a digital instrument may be programmed to generate a sequence of digital values at a test point of a unit under test (“UUT”) and measure one or more digital responses. The digital instrument may then analyze the responses to determine whether the UUT responded as expected to the stimulus signals.
One or more analog instruments may also be included in the test system, with each instrument generating or measuring an analog signal. For example, one analog instrument may act as a digital meter outputting a value that represents a voltage at a test point of a UUT. Another analog instrument may act as a scope, capturing samples of an analog signal at a test point and graphically displaying a representation of that signal. Yet other analog instruments may act as timing triggers, identifying a programmed pattern of signals and outputting an indication when that pattern is detected.
Each test system may include multiple instruments, with the specific instruments incorporated in the test system depending on the characteristics of units expected to be tested with that test system. The instruments may operate in a coordinated fashion under control of circuitry that is programmed to control the instruments to collectively perform any desired test. Outputs from the instruments may be passed to a processing element that determines from individual instruments whether the UUT is functioning, or, if the UUT is defective, determines the nature of the defect.
Many test facilities, whether operated for maintenance or manufacture of units, test multiple types of units with tests including different processes. Accordingly, a test system may be configured with more instruments than needed to test a single unit so that as test needs are identified, instruments needed to perform all processes of any test will be available. A downside of such an approach is the cost of procuring multiple instruments is incurred.